In geometry, trilateration (often alternatively referred to as triangulation) is the process of determining the absolute or relative location of a point in space by measurement of distances, using the geometry of circles, spheres or triangles. Location determination processes, such as Global Positioning Satellite (GPS) services, often use some form of trilateration.
For Wi-Fi (as defined, for example, by 802.11-2012—IEEE Standard for Information technology—Telecommunications and information exchange between systems Local and metropolitan area networks), a station (STA) is any device that contains an IEEE 802.11-conformant medium access control (MAC) and physical layer (PHY) interface to wireless medium (WM).
Trilateration may also be used for indoor location based services where a stationary or mobile device functioning as an STA is capable of receiving Wi-Fi beacon frames from multiple peer devices (PDs), such as Wi-Fi Access Points, laptops, mobile computing devices, beacons and/or fixed devices. PDs are used as reference points in trilateration processes, with the distance between the STA and PD being calculated using wireless signal strength measurements and a wireless propagation model (e.g., Freespace Path Loss Model or Two Ray Model).
Variations in STA movements and signal strengths can cause inaccuracies in trilateration calculations.
Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.